Windows have long been used in various forms. One conventional arrangement, for example, is to provide a solid sash made of wood or the like for holding the glass panes. The sashes are generally mounted to a solid framework which likewise is made of wood. For security measures and other reasons, it is common to provide various types of locks for the windows. Usually the locks are located at the top of the lower sash, although it has also been known to provide side locks.
An improved form of window which has enjoyed wide-spread success is to utilize extrusion techniques to form hollow sashes and framework for the windows, and a particularly desirable variation is to arrange the sashes in such a manner that each of the upper and lower sashes may not only slide vertically to open the window but may also tilt or pivot into the house or building to facilitate cleaning the window. The disadvantage, however, with such arrangements is that by introducing such versatility with the hollow members, it is difficult to maintain an effective seal.